Suspension control for pulse/glide green cruise control

ABSTRACT

A method is described comprising modulating vehicle speed about a target speed by operating a vehicle with an engine at high output and then operating the vehicle with the engine off, and adjusting operation of a suspension system based on the vehicle operation with the engine at high output and the engine off to control vehicle pitch during the modulating of vehicle speed about the target speed.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/734,826, “SUSPENSION CONTROL FOR PULSE/GLIDE GREEN CRUISECONTROL,” filed on Jan. 4, 2013, now U.S. Pat. No. 8,825,293, the entirecontents of which are hereby incorporated by reference for all purposes.

FIELD

The present description relates to improving passenger comfort in avehicle, for example by controlling suspension systems responsive tocruise control systems to reduce vehicle pitching during periods ofacceleration and deceleration.

BACKGROUND AND SUMMARY

Cruise control operation may be used for autonomously regulating avehicle's speed near a target speed. One method that can reduce fuelconsumption while operating cruise control is a Pulse and Glide (PG)speed-control strategy, where time-dependent periodic control of thevehicle's speed is implemented. During the pulse portion of the PGspeed-control strategy, the vehicle is accelerated to a threshold speedabove the target speed. Subsequently, the engine is shut off during theglide portion of the PG speed-control strategy, until the vehicledecelerates to a threshold speed below the target speed. By repeatingthis PG speed-control strategy in a periodic manner, the vehicle can bedriven with an average speed equivalent to a desired target speed, butwith higher fuel economy, by taking advantage of lower pumping lossesduring the pulse phase, during which the engine is operated close to orat wide open throttle.

The inventors herein have recognized potential issues with the PGspeed-control strategy. Namely, because the PG speed-control strategyrequires alternating periods of acceleration (e.g., pulsing) anddeceleration (e.g., gliding), it can also cause periodic pitching of thevehicle (e.g., nose-up or squatting during pulsing, nose-down or divingwhile gliding) that can cause ride discomfort, especially for longdrives.

One approach that addresses the aforementioned issues is a method thatcoordinates or synchronizes control of the vehicle suspension systemswith PG speed-control strategy. In one example, a vehicle's activesuspension can increase stiffness at the vehicle's rear wheels duringacceleration, and can increase stiffness at the vehicle's front wheelsduring deceleration. In this way, the overall ride comfort can beincreased, while still enabling fuel economy gains.

In another example, during pulsing and gliding, the method adjusts thevehicle suspension to reduce variation in vehicle height (e.g., frontvehicle height), thereby reducing ride discomfort, while maintainingfuel economy. In another example, the method can pre-adjust the vehiclesuspension in anticipation of the pulsing and gliding disturbances,based on the PG speed-control parameters, in order to further reduceride discomfort while maintaining fuel economy.

The above advantages as well as other advantages, and features of thepresent description will be readily apparent from the following DetailedDescription when taken alone or in connection with the accompanyingdrawings.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of an example propulsion system for a vehicle,including an engine, energy storage device, fuel system, and motor.

FIG. 2 shows a schematic of an example engine, including a cylinder,exhaust-gas aftertreatment device, and engine controller, which may beincluded in the propulsion system of FIG. 1.

FIG. 3 is a schematic illustrating pulse and glide operation and fueleconomy benefits that may be derived therefrom.

FIG. 4 is a schematic illustrating an example method of determiningfront and rear vehicle heights.

FIG. 5 is a block diagram illustrating an example configuration of apowertrain control module for coordinating suspension control with pulseand glide cruise control.

FIG. 6 is a flow chart illustrating an example method for coordinatingsuspension control to assist pulse and glide cruise control.

FIG. 7 is a flow chart illustrating an example method for coordinatingsuspension control to assist pulse glide cruise control.

FIG. 8 is a flow chart illustrating an example method for coordinatingsuspension control to assist pulse glide cruise control.

FIG. 9 is a block diagram illustrating an example configuration ofvarious electronic control units (ECUs) in a controller area network(CAN).

DETAILED DESCRIPTION

The present description relates to improving passenger comfort in avehicle by controlling suspension systems responsive to cruise controlsystems to reduce vehicle pitching during periods of acceleration anddeceleration. FIG. 1 illustrates an example of a propulsion system for avehicle comprising an engine, motor, generator, fuel system and controlsystem. FIG. 2 illustrates an example of an internal combustion engine,although the systems and method disclosed can be applicable tocompression ignition engines and turbines, or motorized electricvehicles without a combustion engine. FIG. 3 shows two chartsillustrating Pulse and Glide (PG) operation in a vehicle and itspotential impact on fuel economy. FIG. 4 shows a schematic illustratingvehicle height as it relates to vehicle suspension systems. FIG. 5illustrates an example configuration of powertrain control module forcoordinating suspension control with pulse and glide cruise control.FIGS. 6-8 show flow charts illustrating routines for coordinatingsuspension control with PG cruise control operation. FIG. 9 illustratesan example configuration of various electronic control units (ECUs) in acontroller area network (CAN).

Turning now to FIG. 1, it illustrates an example of a vehicle propulsionsystem 100. Vehicle propulsion system 100 may comprise a fuel burningengine 110 and a motor 120. As a non-limiting example, engine 110comprises an internal combustion engine and motor 120 comprises anelectric motor. As such, vehicle propulsion system 100 may be apropulsion system for a hybrid-electric vehicle. However, vehiclepropulsion system may also be a propulsion system for a non-hybridvehicle, or an electric vehicle with an electric motor and no combustionengine. Motor 120 may be configured to utilize or consume a differentenergy source than engine 110. For example, engine 110 may consume aliquid fuel (e.g., gasoline) to produce an engine output while motor 120may consume electrical energy to produce a motor output. As such, avehicle with propulsion system 100 may be referred to as a hybridelectric vehicle (HEV). In other examples, where the vehicle propulsionsystem 100 is for an electric vehicle, vehicle propulsion system may bereferred to as an electric vehicle (EV).

Vehicle propulsion system 100 may utilize a variety of differentoperational modes depending on operating conditions encountered by thevehicle propulsion system. Some of these modes may enable engine 110 tobe maintained in an off state (e.g. set to a deactivated state) wherecombustion of fuel at the engine is discontinued. For example, underselect operating conditions, motor 120 may propel the vehicle via drivewheel 130 as indicated by arrow 122 while engine 110 is deactivated.

During other operating conditions, engine 110 may be set to adeactivated state (as described above) while motor 120 may be operatedto charge energy storage device 150 such as a battery. For example,motor 120 may receive wheel torque from drive wheel 130 as indicated byarrow 122 where the motor may convert the kinetic energy of the vehicleto electrical energy for storage at energy storage device 150 asindicated by arrow 124. This operation may be referred to asregenerative braking of the vehicle. Thus, motor 120 can provide agenerator function in some embodiments. However, in other embodiments,generator 160 may instead receive wheel torque from drive wheel 130,where the generator may convert the kinetic energy of the vehicle toelectrical energy for storage at energy storage device 150 as indicatedby arrow 162.

During still other operating conditions, engine 110 may be operated bycombusting fuel received from fuel system 140 as indicated by arrow 142.For example, engine 110 may be operated to propel the vehicle via drivewheel 130 as indicated by arrow 112 while motor 120 is deactivated.During other operating conditions, both engine 110 and motor 120 mayeach be operated to propel the vehicle via drive wheel 130 as indicatedby arrows 112 and 122, respectively. A configuration where both theengine and the motor may selectively propel the vehicle may be referredto as a parallel type vehicle propulsion system. Note that in someembodiments, motor 120 may propel the vehicle via a first set of drivewheels and engine 110 may propel the vehicle via a second set of drivewheels.

In other embodiments, vehicle propulsion system 100 may be configured asa series type vehicle propulsion system, whereby the engine does notdirectly propel the drive wheels. Rather, engine 110 may be operated topower motor 120, which may in turn propel the vehicle via drive wheel130 as indicated by arrow 122. For example, during select operatingconditions, engine 110 may drive generator 160, which may in turn supplyelectrical energy to one or more of motor 120 as indicated by arrow 114or energy storage device 150 as indicated by arrow 162. As anotherexample, engine 110 may be operated to drive motor 120 which may in turnprovide a generator function to convert the engine output to electricalenergy, where the electrical energy may be stored at energy storagedevice 150 for later use by the motor. The vehicle propulsion system maybe configured to transition between two or more of the operating modesdescribed above depending on vehicle operating conditions. As anotherexample, vehicle propulsion system may be a propulsion system for anelectric vehicle (e.g., with no combustion engine), wherein an electricmotor receiving electric power from energy storage device 150 (e.g., abattery) may propel the vehicle.

Fuel system 140 may include one or more fuel storage tanks 144 forstoring fuel on-board the vehicle. For example, fuel tank 144 may storeone or more liquid fuels, including but not limited to gasoline, diesel,and alcohol fuels. In some examples, the fuel may be stored on-board thevehicle as a blend of two or more different fuels. For example, fueltank 144 may be configured to store a blend of gasoline and ethanol(e.g. E10, E85, etc.) or a blend of gasoline and methanol (e.g. M10,M85, etc.), whereby these fuels or fuel blends may be delivered toengine 110 as indicated by arrow 142. Still other suitable fuels or fuelblends may be supplied to engine 110, where they may be combusted at theengine to produce an engine output. The engine output may be utilized topropel the vehicle as indicated by arrow 112 or to recharge energystorage device 150 via motor 120 or generator 160.

In some embodiments, energy storage device 150 may be configured tostore electrical energy that may be supplied to other electrical loadsresiding on-board the vehicle (other than the motor), including cabinheating and air conditioning, engine starting, headlights, cabin audioand video systems, an exhaust-gas grid heater, an exhaust-gas recyclecooler, etc. As a non-limiting example, energy storage device 150 mayinclude one or more batteries and/or capacitors.

Control system 190 may communicate with one or more of engine 110, motor120, fuel system 140, energy storage device 150, and generator 160. Aswill be described in FIG. 2, control system 190 may comprise controller211 and may receive sensory feedback information from one or more ofengine 110, motor 120, fuel system 140, energy storage device 150, andgenerator 160. Further, control system 190 may send control signals toone or more of engine 110, motor 120, fuel system 140, energy storagedevice 150, and generator 160 responsive to this sensory feedback.Control system 190 may receive an indication of an operator requestedoutput of the vehicle propulsion system from a vehicle operator 102. Forexample, control system 190 may receive sensory feedback from pedalposition sensor 194 which communicates with pedal 192. Pedal 192 mayrefer schematically to a brake pedal and/or an accelerator pedal.

Energy storage device 150 may periodically receive electrical energyfrom a power source 180 residing external to the vehicle (e.g. not partof the vehicle) as indicated by arrow 184. As a non-limiting example,vehicle propulsion system 100 may be configured as a plug-in hybridelectric vehicle (HEV), whereby electrical energy may be supplied toenergy storage device 150 from power source 180 via an electrical energytransmission cable 182. As a further non-limiting example, vehiclepropulsion system 100 may be configured as a plug-in electric vehicle(EV), whereby electrical energy may be supplied to energy storage device150 from power source 180 via an electrical energy transmission cable182. Control system 190 may further control the output of energy orpower from energy storage device 150 (e.g., a battery) depending on theelectric load of vehicle propulsion system 100. For example, duringreduced electrical load operation, control system 190 may step-down thevoltage delivered from energy storage device 150, via a aninverter/converter, in order to save energy.

During a recharging operation of energy storage device 150 from powersource 180, electrical transmission cable 182 may electrically coupleenergy storage device 150 and power source 180. While the vehiclepropulsion system is operated to propel the vehicle, electricaltransmission cable 182 may be disconnected between power source 180 andenergy storage device 150. Control system 190 may identify and/orcontrol the amount of electrical energy stored at the energy storagedevice, which may be referred to as the state of charge(state-of-charge).

In other examples, electrical transmission cable 182 may be omitted,where electrical energy may be received wirelessly at energy storagedevice 150 from power source 180. For example, energy storage device 150may receive electrical energy from power source 180 via one or more ofelectromagnetic induction, radio waves, and electromagnetic resonance.As such, it will be appreciated that any suitable approach may be usedfor recharging energy storage device 150 from a power source that doesnot comprise part of the vehicle. In this way, motor 120 may propel thevehicle by utilizing an energy source other than the fuel utilized byengine 110.

Fuel system 140 may periodically receive fuel from a fuel sourceresiding external to the vehicle. As a non-limiting example, vehiclepropulsion system 100 may be refueled by receiving fuel via a fueldispensing device 170 as indicated by arrow 172. In some embodiments,fuel tank 144 may be configured to store the fuel received from fueldispensing device 170 until it is supplied to engine 110 for combustion.

A plug-in hybrid electric vehicle, as described with reference tovehicle propulsion system 100, may be configured to utilize a secondaryform of energy (e.g. electrical energy) that is periodically receivedfrom an energy source that is not otherwise part of the vehicle.

The vehicle propulsion system 100 may also include a message center 196,ambient temperature/humidity sensor 198, electrical load sensor 154, anda roll stability control sensor, such as a lateral and/or longitudinaland/or steering wheel position or yaw rate sensor(s) 199. The messagecenter may include indicator light(s) and/or a text-based display inwhich messages are displayed to an operator, such as a messagerequesting an operator input to start the engine, as discussed below.The message center may also include various input portions for receivingan operator input, such as buttons, touch screens, voiceinput/recognition, GPS device, etc. In an alternative embodiment, themessage center may communicate audio messages to the operator withoutdisplay. Further, the sensor(s) 199 may include a vertical accelerometerto indicate road roughness and a lateral accelerometer. These devicesmay be connected to control system 190. In one example, the controlsystem may adjust engine output and/or the wheel brakes to increasevehicle stability in response to sensor(s) 199.

Next, vehicle propulsion system may further comprise one or more vehicleheight sensors 197 to indicate the vehicle height. As an example, theremay be a single vehicle height sensor, or there may be a front vehicleheight sensor and a rear vehicle height sensor indicating the front andrear vehicle heights respectively (see FIG. 4). In a further example,there may be more than two vehicle height sensors, for example, fourvehicle height sensors, corresponding to each wheel of vehiclepropulsion system 100. As such, control system 190 may adjust thevehicle suspension in order to increase or decrease one or more vehicleheights according to one or more respective vehicle height sensors 197.

Referring now to FIG. 2, it illustrates a non-limiting example of acylinder 200 of engine 110, including the intake and exhaust systemcomponents that interface with the cylinder. Note that cylinder 200 maycorrespond to one of a plurality of engine cylinders. Cylinder 200 is atleast partially defined by combustion chamber walls 232 and piston 236.Piston 236 may be coupled to a crankshaft 240 via a connecting rod,along with other pistons of the engine. Crankshaft 240 may beoperatively coupled with drive wheel 130, motor 120 or generator 160 viaa transmission.

Cylinder 200 may receive intake air via an intake passage 242. Intakepassage 242 may also communicate with other cylinders of engine 110.Intake passage 242 may include a throttle 262 including a throttle plate264 that may be adjusted by control system 190 to vary the flow ofintake air that is provided to the engine cylinders. Cylinder 200 cancommunicate with intake passage 242 via one or more intake valves 252.Cylinder 200 may exhaust products of combustion via an exhaust passage248. Cylinder 200 can communicate with exhaust passage 248 via one ormore exhaust valves 254.

In some embodiments, cylinder 200 may optionally include a spark plug292, which may be actuated by an ignition system 288. A fuel injector266 may be provided in the cylinder to deliver fuel directly thereto.However, in other embodiments, the fuel injector may be arranged withinintake passage 242 upstream of intake valve 252. Fuel injector 266 maybe actuated by a driver 268.

A non-limiting example of control system 190 is depicted schematicallyin FIG. 2. Control system 190 may include a processing subsystem (CPU)202, which may include one or more processors. CPU 202 may communicatewith memory, including one or more of read-only memory (ROM) 206,random-access memory (RAM) 208, and keep-alive memory (KAM) 210. As anon-limiting example, this memory may store instructions that areexecutable by the processing subsystem. The process flows,functionality, and methods described herein may be represented asinstructions stored at the memory of the control system that may beexecuted by the processing subsystem.

CPU 202 can communicate with various sensors and actuators of engine110, energy storage device 150, and fuel system 140 via an input/outputdevice 204. As a non-limiting example, these sensors may provide sensoryfeedback in the form of operating condition information to the controlsystem, and may include: an indication of mass airflow (MAF) throughintake passage 242 via sensor 220, an indication of manifold airpressure (MAP) via sensor 222, an indication of throttle position (TP)via throttle 262, an indication of engine coolant temperature (ECT) viasensor 212 which may communicate with coolant passage 214, an indicationof engine speed (PIP) via sensor 218, an indication of exhaust gasoxygen content (EGO) via exhaust gas composition sensor 226, anindication of intake valve position via sensor 255, an indication ofexhaust valve position via sensor 257, an indication of electrical loadvia electrical load sensor 154, and an indication of proximity tovehicle traffic (e.g. distance from another vehicle traveling in frontof via one or more vehicle presence sensors 298. For example, vehiclepresence sensors 298 may include radar, laser, video, infrared,ultrasound, and image sensors, and/or combinations thereof to detect thepresence of other vehicles in the vicinity of the vehicle.

Furthermore, the control system 190 may control operation of the engine110, including cylinder 200 via one or more of the following actuators:driver 268 to vary fuel injection timing and quantity, ignition system288 to vary spark timing and energy, intake valve actuator 251 to varyintake valve timing, exhaust valve actuator 253 to vary exhaust valvetiming, and throttle 262 to vary the position of throttle plate 264,among others. Note that intake and exhaust valve actuators 251 and 253may include electromagnetic valve actuators (EVA) and/or cam-followerbased actuators. Further still, control system 190 may control or adjustactuators associated with the operation of the vehicle suspension.

Turning now to FIG. 3, it illustrates a first chart 310, illustrating anexample of PG operation. In this example of PG operation, a vehicletravels with an average speed of 80 km/h, a target speed. As shown bythe oscillating speed profile, PG operation comprises modulating thevehicle speed about the target speed (e.g., 80 km/h) over a thresholdinterval of 20 km/h. In other words, the vehicle first accelerates(e.g., pulse phase) from a speed of 70 km/h to a speed of 90 km/h.Subsequently, the vehicle decelerates (e.g., glide phase) from the speedof 90 km/h over the threshold interval, returning to the speed of 70km/h. Repetition of the pulse and glide phases of the vehicle occurscontinuously during PG operation. The modulation period of the PGoperation is the time to complete one pulse and one glide phase. In theexample illustrated in chart 310, the modulation period is 32 seconds.The modulation frequency is the reciprocal of the modulation period. Forexample, in chart 310, the modulation frequency is 1/32 s⁻¹.

PG operation may aid fuel economy since fuel consumption is limited toengine operation during the pulse phases, where the engine operates atmore efficiently at high output to accelerate the vehicle. During theglide (e.g., deceleration) phases, the engine is off, and fuel is notconsumed by the engine. Chart 320 illustrates the potential fuel economybenefits to PG operation. Under non-PG operation of the vehicle at asteady target speed (e.g., 80 km/h), the fuel economy is 59 miles pergallon (mpg). Under PG operation of the vehicle with an equivalentaverage speed equal to the target speed (e.g., 80 km/h), the fueleconomy is estimated to increase to 68 mpg. Fuel economy benefitsafforded by PG operation as compared to steady non-PG operation maydepend on several parameters such as vehicle type, engine type, vehiclespeed, road grade, and the like.

Turning now to FIG. 4 it illustrates a schematic of a vehicle 400.Vehicle 400 may comprise vehicle propulsion system 100 of FIG. 1, andcylinder 200 of engine 110. Vehicle height H1 can refer to the frontvehicle height of the vehicle and can comprise the height of the frontwheel well, whereas H2 can refer to the rear vehicle height of thevehicle and can comprise the height of the rear wheel well, as depictedin FIG. 4. Vehicle 400 may also comprise additional vehicle heights(e.g. H3, H4, and the like, not shown) wherein each vehicle heightcorresponds to the vehicle height at each vehicle drive wheel 130. Aspreviously discussed, vehicle 400 may also comprise vehicle heightsensors 197 that communicate one or more vehicle heights to controlsystem 190.

Under certain conditions while the vehicle is in operation, vehicleheights may change relative to one another, at least momentarily. Forexample, when the vehicle accelerates, the rear vehicle height maycompress relative to the front vehicle height (e.g., H2<H1), giving riseto nose-up vehicle squat during the acceleration period. Conversely,when the vehicle decelerates or brakes, the front vehicle height maycompress relative to the rear vehicle height (e.g., H1<H2), and thevehicle may pitch forward or dive (e.g., nose-down) during thedeceleration period. Accordingly, it may be desirable for reducingpassenger discomfort, vehicle operation, vehicle life, and the like, tocontrol the individual vehicle heights such that equivalent vehicleheights are maintained during periods of acceleration and deceleration.

Turning now to FIG. 5, it illustrates an example of a configuration of aPowertrain Control Module (PCM) 510 of a vehicle propulsion system 100for a vehicle 400. PCM 510 may reside in CPU 202 of control system 190,and may comprise, for example, a Pulse and Glide (PG) Strategy submodule550. PCM 510 may communicate with Controller Area Network (CAN) 502, andCAN 502 may communicate with other ECU modules such as Vehicle DynamicsControl Module (VDCM) 512. Both PCM 510 and VDCM 512 may receiveinformation from vehicle sensors 590 via CAN 502, and output signals tovehicle actuators 570 via signals 506 and 508, and 509 respectively.

As a non-limiting example, vehicle sensors 590 may provide sensoryfeedback in the form of operating condition information to the PCM 510via CAN 502. Vehicle sensors 590 may comprise above-mentioned sensorssuch as vehicle presence sensors 197 and other sensors 199, such aslateral and/or longitudinal and/or steering wheel position, yaw rate,and lateral and vertical accelerometer sensors. Vehicle sensors 590 mayfurther comprise wheel sensors for measuring wheel torque and wheelrotational speed, imaging sensors for detecting road and trafficconditions and vehicle positioning relative to the road. Further still,vehicle sensors 590 may comprise other above-described sensorsillustrated in FIG. 2.

Vehicle actuators 570 may comprise brake actuators such as brakehydraulic valves and pumps, for example, for operating the ABS. Vehicleactuators 570 may also comprise suspension system actuators such ashydraulic pumps, electromagnetic motors, solenoid valves, andelectromagnetic actuators. Vehicle actuators 570 may further compriseother above-mentioned actuators illustrated in FIG. 2, and may furtherbe actuated by control system 190 for controlling engine 110 operationsuch as driver 268, ignition system 288, intake valve actuator 251,exhaust valve actuator 253, and throttle 262, among others.

VDCM 512 may be used to control the actuators of a vehicle suspensionsystem, which may be an active or semi-active suspension system. Anactive suspension system may comprise hydraulic pump actuatedsuspensions to independently adjust the suspension and/or vehicle heightat each wheel to counteract vehicle pitching while in motion. As afurther example, an active suspension system may also comprise anelectromagnetic recuperative suspension wherein linear electromagneticmotors may be attached to each wheel to independently adjust thesuspension and/or vehicle height at each wheel. An active suspensionsystem may also comprise an adaptive (e.g. semi-active) suspensionsystem. For example, solenoid valve actuators may be employed to varythe flow of hydraulic fluid inside the suspension system shocks tochange the damping characteristics of the suspension. As a secondexample of an adaptive suspension system, electromagnetic actuators maybe used to change the stiffness of wheel suspensions comprising magnetorheological dampers. Other types of active, semi-active, and othersuspensions systems may also be used and controlled by VDCM 512.

PG Strategy submodule 550 may comprise systems for monitoring anddetermining the road condition 552, driving condition 554, drivercharacterization 556, and operation priority 558. PG Strategy submodule550 may also communicate with a Cruise Control/Forward Sensing module514 (FIG. 9) to coordinate PG operation with strategies and controls forfeatures associated with a Smart Adaptive Cruise Control (SACC) systemsuch as distance control to follow a vehicle at a set distance, or speedcontrol to follow a target velocity value.

As shown in FIG. 5, PG Strategy Submodule 550 may operate using PG SpeedTarget 520. For example, PG strategy Submodule 550 may communicate withthe vehicle Cruise Control/Forward Sensing Module 514 via CAN 502 inorder to modulate vehicle speed corresponding to the PG Speed Target520. PG Strategy Submodule 550 may also use road condition 552, drivingcondition 554, driver characterization 556, and operation priority 558system information for determining a PG Speed Target 520. PCM 510 mayfurther receive an indication of the current vehicle speed 504 fromvehicle sensors 590 and produce an output signal to vehicle actuators570 based on vehicle speed 504 and PG Speed Target 520.

As a further example, PG Strategy Submodule 550 may communicate with thevehicle Cruise Control/Forward Sensing Module 514 via CAN 502 in orderto maintain a Following Distance Target (e.g. to maintain a targetfollowing distance from a vehicle in front of the host vehicle). Furtherstill, PG Strategy submodule 550 may communicate with the vehicle CruiseControl/Forward Sensing Module 514 via CAN 502 to maintain vehicle speedaccording to both a PG Speed Target 520 and a Following Distance Target.

PG Strategy Submodule 550 may also use above information (e.g. the roadcondition 552, driving condition 554, driver characterization 556, andoperation priority 558) for PG Suspension Control 524 that outputssignals to VDCM 512. For example, PG Strategy Submodule 550 may receiveinput from vehicle sensors 590 via CAN 502 and determine road condition552, driving condition 554, driver characterization 556, and operationpriority 558 based on the received sensory information. PG StrategySubmodule 550 may then provide direction to set the PG Speed Target 520and/or setpoints for the PG Suspension control 524. Furthermore PGStrategy Submodule 550 may then communicate with the vehicle CruiseControl/Forward Sensing Module 514 via CAN 502 in order to maintain aFollowing Distance Target, or to modulate vehicle speed corresponding tothe PG Speed Target 520.

For example, PG Strategy submodule 550 may receive via CAN 502 locationor route information from GPS and road sensors that communicate presentand upcoming changes in road speed limits, traffic and weatherconditions. As a further example, PG Strategy submodule 550 may receiveinformation about the speed of and distance from the vehicle in front ofthe user's vehicle from laser, radar or ultrasonic sensors such asvehicle presence sensors 298 via CAN 502. In particular, if PG Strategysubmodule 550 receives information about wet roads, a reduction in roadspeed limit, or slow traffic ahead, PG Strategy submodule 550 may reducethe PG Speed Target 520 and may communicate with the vehicle CruiseControl/Forward Sensing Module 514 via CAN 502 in order to increase aFollowing Distance Target. Subsequently, PG Strategy submodule 550 mayactuate appropriate actuators of vehicle actuators 570 in order to meetthe updated PG Speed Target 520 and/or Following Distance Target.Furthermore, adjustment of PG Speed Target 520 may instigate aconcomitant adjustment to the Following Distance Target, and vice-versa.For example, an increase in the Following Distance Target may accompanyan increase in PG Speed Target 520. Alternately, the user may manuallyinput PG Speed Target 520 and/or a Following Distance Target.

Further still, in response to sensory input, PG Strategy submodule 550may update PG Suspension Control parameters. For example if the PGStrategy submodule 550 increases PG Speed Target 520 in response tosensory input, PG Strategy submodule 550 may also adjust PG SuspensionControl parameters to anticipate and prevent vehicle pitching. Forinstance, PG Strategy submodule may output a signal to VDCM 512 to firmrear wheel suspensions in order to mitigate vehicle squat as the vehicleaccelerates to the higher PG Speed Target 520.

Under certain conditions, a vehicle SACC may operate in a speed-basedcruise control mode, solely using an SACC Velocity Target, for examplemodulating vehicle speed corresponding to a PG Speed Target, whendriving on a freeway under light traffic conditions, for example, wherea distance d to a vehicle traveling in front of vehicle 400 is greaterthan a threshold distance, d_(pg,upper). Under these circumstances, theCruise Control/Forward Sensing Module 514 may not set an FollowingDistance Target, and may not monitor the distance, d, to a vehicletraveling in front of vehicle 400 (e.g., the host vehicle). Undercertain other conditions, for example when vehicle 400 is followinganother vehicle, SACC may operate in adaptive cruise control mode, whereboth an SACC Velocity Target and an SACC Following Distance Target maybe used. During adaptive cruise control mode, SACC may prioritizemaintaining a distance, d, from a vehicle travelling in front of vehicle400, and thereby adjust the SACC Velocity Target accordingly.

The configuration in FIG. 5 also comprises Driver Warning/AdvisorySystem 560, which may receive input from PG Strategy submodule 550. Forexample, if PG Strategy submodule 550 receives sensory information viaCAN 502 from vehicle sensors 590 indicating foggy or reduced visibilityroad conditions ahead, PG Strategy submodule 550 may assign an OperationPriority 558 to reducing the PG Speed Target 520, and increasing theFollowing Distance Target, and may send an advisory warning to theDriver 540 via the Driver Warning/Advisory System 560 and CAN 502.Driver 540 may further receive other inputs 564. In response, Driver540, may then activate Vehicle Actuators 570, for example, turning onthe vehicle lights, or the vehicle fog headlights if available, and byapplying brakes to reduce vehicle speed.

Turning now to FIG. 9, CAN 502 may manage communication to and from andbetween several ECU modules for vehicle 400 such as VCDM 512, CruiseControl/Forward Sensing Module 514, Anti-Lock Braking System (ABS)Module 516, PCM 510 and other modules 519. As previously discussed, VDCM512 may output signals for controlling an active or semi-active(adaptive) suspension system. Cruise Control/Forward Sensing Module 514may include control strategies for Smart Adaptive Cruise Control (SACC),Forward Collision Warning, Collision Mitigation systems, Lane DepartureWarning, and the like. ABS Module 516 may include ABS/Traction ControlSystems (ABS/TCS), Electronic Stability Control/Roll Stability Control(ESC/RSC) systems, Curve control, and the like. PCM 510 may includeAir-fuel Ratio Control, Variable Cam Timing, and Fuel Economy Managersystems. The Fuel Economy Manager may control Pulse & Glide strategy forthe vehicle, among other functions related to maintaining or improvingfuel economy. For example, Fuel Economy Manager may also send outputs tothe VDCM 512 to lower the vehicle height to reduce drag when the vehicleis travelling at high speeds (e.g., freeway driving).

As an example, the ABS system may actuate the brake hydraulics to reducehydraulic pressure and transmit brake pulsation to wheels that arerotating significantly slower than other wheels, to avoid impendingwheel lock. As a further example, ESC system may sense that the vehiclehas lost traction (e.g., skidding) when the intended vehicle directiondetermined through the steering angle does not match the actual vehicledirection of motion as determined through the lateral accelerometer,vehicle yaw, or individual wheel speeds. Accordingly, the ESC system mayactuate the hydraulic brake actuators to apply the brakes to individualwheels to help return the actual vehicle direction of motion to thatintended. ESC system may also work in conjunction with other ECU modulessuch as TCS to mitigate loss of traction and to increase vehiclestability. For example, under slippery road conditions, TCS may limitthe engine torque during vehicle acceleration to below a minimumtraction torque threshold, above which TCS is triggered, so as to reducetraction or energy loss due to wheel spinning.

In addition to receiving sensory input from vehicle sensors 590 via CAN502, ECU modules 512, 514, 516, 510, and 519 may further send outputsignals to vehicle actuators 570. Furthermore, as discussed above forFIG. 5, CAN 502 may communicate with Driver Warning System/DriverAdvisory System 560. Driver 540 may thus receive notifications fromDriver Warning System/Driver Advisory System 560 related, for example toone or more of ECU modules 512, 514, 516, 510, and 519, and may alsoreceive other inputs 564. Driver 540 may also receive sensory inputinformation from vehicle sensors 590 and send outputs to vehicleactuators 570.

As a further example, Fuel Economy Manager may also interact with CruiseControl/Forward Sensing Module 514, by providing inputs to the SACCVelocity Target corresponding to the PG speed-control strategy. Forexample, PG speed-control strategy may provide inputs of a PG SpeedTarget, and a threshold interval for modulating the vehicle speed aboutthe PG target speed. Based on the desired PG Speed Target and thresholdinterval, the Fuel Economy Manager, or another ECU where the PGspeed-control strategy resides, may output an SACC Velocity Target toCruise Control/Forward Sensing Module 514 corresponding to the PGspeed-control strategy.

For example, if the PG Speed Target 520 is set at 60 miles per hour(mph), and the PG threshold interval is 10 mph, the Fuel Economy Manager(e.g., where the PG Strategy submodule 550 resides) may first output anSACC Velocity Target of 65 mph, in order to begin a pulse phase of thePG speed-control strategy. Subsequently, the Cruise Control/ForwardSensing Module 514 may increase the throttle 262 to operate one or moreengine cylinders, for example, to begin acceleration of the vehicle to65 mph. Fuel Economy Manager, upon receiving information from VehicleSensors 590 that the vehicle has reached the pulse phase PG Speed Target520, may then output signal to Cruise Control/Forward Sensing Module 514to reduce the SACC Velocity Target to 55 mph to begin a glide phase.During the glide phase, Cruise Control/Forward Sensing Module 514 mayshut off the engine to decelerate the vehicle. Alternately, CruiseControl/Forward Sensing Module 514 may deactivate one engine cylinder,multiple engine cylinders, or all engine cylinders to decelerate thevehicle to the glide phase velocity target of 55 mph. Duringdeactivation of one or multiple cylinders, the remaining active enginecylinders may continue to carry out combustion. Furthermore, during thedeactivation of engine cylinders for deceleration during the glidephase, the engine may continue to rotate, or it may decrease to rest.

Further still, Cruise Control/Forward Sensing Module 514 may output asignal to VDCM 512 via CAN 502 to adjust or control an active suspensionsystem in conjunction with SACC Velocity Target and/or SACC FollowingDistance Target in order to reduce vehicle pitching to maintainnear-constant vehicle height and passenger comfort. For example, anincrease in the SACC Velocity Target may initiate vehicle accelerationthat may cause the vehicle to momentarily squat. Accordingly, the CruiseControl/Forward Sensing Module 514 may output adjustments to the VDCM512 via CAN 502 in order to mitigate this vehicle pitching, for example,by firming the rear shocks, and/or raising the rear suspension heights.Alternately, VDCM 512 may receive an input of a change to the SACCVelocity Target and subsequently make corresponding adjustments to thesuspension system.

In some cases, PCM 510 may coordinate control of the VCDM 512 with PGStrategy submodule 550 and Cruise Control/Forward Sensing Module 514 inorder to anticipate changes to the SACC Velocity Target and/or SACCFollowing Distance Target. For example, VDCM 512 may receive SACCVelocity Target and SACC Following Distance Target as inputs from CruiseControl/Forward Sensing Module 514, and in response, VDCM 512 maypre-adjust the Active Suspension System in order to counteract orprevent vehicle pitching resulting from impending vehicle accelerationor deceleration corresponding to the changing Cruise Control/ForwardSensing Module 514 target parameters. For example, the CruiseControl/Forward Sensing Module 514 may receive sensory input ofimpending heavy traffic and in response, lower the SACC Velocity Target.Concurrently, VDCM 512 may, upon receiving as input the change to theSACC Velocity Target, firm or raise the front suspension in anticipationof the impending vehicle deceleration. Furthermore, CruiseControl/Forward Sensing Module 514 may communicate an advisory warningvia Driver Warning/Advisory System 560 informing the driver 540 of theheavy traffic conditions ahead, and the corresponding adjustments madeto the vehicle speed and suspension systems. In this manner, passengersmay experience minimal or reduced discomfort due to maintaining anear-constant vehicle height and a reduction in vehicle pitching (e.g.,dive) when the vehicle decelerates.

Further still, VDCM 512 control may be coordinated with PGspeed-control. For example, during pulsing and gliding, PCM 510 may,based on PG parameters (e.g., target speed, modulation period, currentcondition within the pulse/glide operation, and the like), output asignal via CAN 502 to VDCM 512 to adjust the vehicle suspension systemto maintain a constant or near constant front vehicle height or reducedisturbances to vehicle height, thereby reducing ride discomfort whilemaintaining fuel economy. For example, the VDCM 512 may pre-adjust oneor more of the front and rear suspension systems just prior to orsimultaneously with the start of the pulse (e.g., acceleration) andglide (e.g., deceleration) phases. As another example, the VDCM 512 maytrack the progression of the vehicle speed profile along an expectedpulse/glide speed profile in order to predict upcoming changes insuspension forces due to activation and deactivation of enginecylinders. Accordingly, VDCM 512 may control the vehicle suspensionsystem in a feed-forward manner based on the current speed as comparedto the anticipated speed at which such activation or deactivation isscheduled, rejecting the disturbances to vehicle height from the pulsingand gliding phases.

Further still, the amplitude and/or period of the PG operation may belimited by the PCM 510 based on the range of authority of the suspensionsystem, and may further depend on the average vehicle speed, roadsurface roughness, road grade, and trailer tow status. For example,under conditions where the vehicle is travelling on a smooth and levelroad, VDCM 512 may be able to control vehicle height and vehiclepitching to maintain passenger comfort, even for PG operation withlarger PG amplitudes and longer PG periods (e.g., smaller PGfrequencies), and thus the PG operation (amplitude, period) may not belimited, or may be limited by a lesser amount. As a further example, oneor more of PG amplitude and PG period may be reduced by PCM 510 underconditions where the vehicle is traveling on a rough road, up a steepgrade, or when towing a trailer or heavily loaded as compared toconditions where the vehicle is travelling on a smooth and level road,so that VDCM 512 can control vehicle height and vehicle pitch during PGoperation to maintain passenger comfort without bottoming the suspensionsystem or other degraded performance. Furthermore, when the vehicle istravelling up a steep grade, PG amplitude may be reduced as compared towhen travelling on a level road in order to avoid long periods ofacceleration uphill and to maintain fuel economy. As a further example,PG amplitudes and periods may be smaller for vehicles with semi-active(e.g., adaptive) suspension systems where damping can be adjusted, ascompared to PG amplitudes and periods for vehicles with activesuspension systems where both damping and vehicle height may beindependently controlled at each wheel.

In this manner, a vehicle may comprise an engine, a suspension system,and a controller. The controller may comprise instructions executable tomodulate vehicle speed about a target speed by operating the vehiclewith the engine at high output and then operating the vehicle with theengine off, and adjust operation of the suspension system based onoperating the vehicle with the engine at high output and the engine offto control vehicle pitch during the modulating of vehicle speed aboutthe target speed. Furthermore, the suspension system comprises a leastone of an active suspension system and a semi-active suspension system,and the controller comprises a smart adaptive cruise control system.

Turning now to FIG. 6, it illustrates a flow chart of an example method600 for coordinating an SACC system of the Cruise Control/ForwardSensing Module 514 with PG speed-control (PG Strategy submodule 550) andthe VDCM 512 to reduce passenger discomfort while maintaining fueleconomy. Method 600 begins at 610, where the vehicle operatingconditions may be obtained, for example, via vehicle sensors 590. Method600 continues at 620, where it may determine if the vehicle 400 isoperating in a Quasi-Straight line (QS) driving manner. PCM 510 maydetermine if vehicle 400 is operating in a QS driving manner fromsensory information. For example, if the driver steering wheel angle isbelow a threshold steering angle, or an electronic horizon (EH) sensorindicates a straight road ahead in the driving route, it may bedetermined that the vehicle is operating in a QS driving manner. If thevehicle is not operating in a QS driving manner, method 600 ends. Forexample, to maintain vehicle operability, PG speed-control strategy maynot be activated when the vehicle is not operating in a QS drivingmanner, such as during high traffic urban driving.

If the vehicle is operating in a QS driving manner, method 600 maycontinue at 630 where it may determine if the distance from anothervehicle in front of vehicle 400 (e.g., the host vehicle), d, is greaterthan d_(pg,upper), a PG speed-control strategy upper distance. Thedistance, d, to another vehicle in front of vehicle 400 may bedetermined using one or more of vehicle presence sensors 298, forexample, one or more of radar, laser, video, infrared, ultrasound, andimage sensors. If d>d_(pg,upper), for example during light freewaytraffic conditions, method 600 may continue at 640 and determine ifspeed-based cruise control, (e.g., SACC based on only SACC VelocityTarget) is activated. For example, method 600 may determine if SACC hasbeen activated by Cruise Control/Forward Sensing Module 514 via driverinput. If speed-based cruise control is off, then method 600 ends.

Next, method 600 may continue at 650, where it may determine ifQuasi-Straight line driving Pulse & Glide (QSPG) strategy of PG Strategysubmodule 550 is active. If QSPG is off, method 600 ends. Otherwise,method 600 continues at 660 where control of the suspension system, e.g.an active suspension system, may be coordinated using VDCM 512 with QSPGand the speed-based cruise control. FIG. 7 provides further exampledetails of how suspension control may be coordinated with QSPG operationusing speed-based cruise control.

Continuing from FIG. 6 at 630, if d<d_(pg,upper), method 600 continuesat 636 where it determines if distance, d, to another vehicle in frontof vehicle 400 is greater than d_(pg,lower), a PG speed-control strategylower distance, and less than d_(pg,upper). If d<d_(pg,lower), method600 ends. If d_(pg,lower) d<d_(pg,upper), then method 600 continues at646 where it determines if the SACC is operating in adaptive cruisecontrol mode. If SACC is not operating in adaptive cruise control mode,then method 600 ends. Otherwise, method 600 continues at 656 where itdetermines if the Adaptive Quasi-Straight line driving Pulse & Glide(AQSPG) mode is on. If AQSPG is off, then method 600 ends. Otherwise,method 600 continues at 670 where suspension control is coordinated toassist AQSPG operation with adaptive cruise control. FIG. 8 providesfurther example details of how suspension control may be coordinated toassist with AQSPG operation with adaptive cruise control.

Turning now to FIG. 7, it illustrates an example method 700 forcoordinating speed-based cruise control of Cruise Control/ForwardSensing Module 514 with control of the suspension system, for example anactive suspension system, via VDCM 512, and PG speed-control strategy.Method 700 begins at 710, where it determines if the PG speed-controlstrategy is currently in a pulse phase. If the vehicle 400 is currentlyoperating in a pulse phase, method 700 continues at 720 where itdetermines if vehicle 400 has an active suspension system. If thevehicle has an active suspension system, method 700 continues at 730where Quasi-Straight line driving Pulse (QSP) leveling is performed. Forexample, during pulse phases, heavy throttle application or operation ofone or more cylinders to increase vehicle speed can lead to vehiclenose-up and rear-down (e.g., vehicle squat) increasing passengerdiscomfort and vehicle air resistance. To counteract vehicle squat, QSPLeveling may reduce front suspension heights, increase rear suspensionheights, and firm the rear suspension, or one or more thereof, in orderto maintain a constant or near-constant vehicle height during the pulsephase. In addition, QSP Leveling may also pre-position one or more ofthe vehicle heights and pre-adjust suspension actuators just prior to orat the start of the pulse phase in anticipation of the impending pulsephase disturbance. In this manner, vehicle pitching induced by vehicleacceleration during pulsing can be further reduced. Next, method 700continues at 750 where QSP Traction Firming may be performed. Forexample, QSP Traction Firming may firm one or more of the wheelsuspension systems to increase fraction at one or more wheels. As afurther example, during the pulse phase, if the throttle 262 is above athreshold engine throttle, QSP Traction Firming may firm one or more ofthe wheel suspension systems to increase or fully utilize the tractioncapabilities at one or more wheels. As a further example, suspensiondamping may be engaged to its maximum value when the engine is above athreshold engine throttle, in order to provide traction firming.

Returning to method 700 at 720, if vehicle 400 does not have an activesuspension system, method 700 continues at step 740, where QSP MotionDamping may be performed for vehicles equipped with semi-active(adaptive) suspension systems or controllable dampers (e.g., shocks).For example, suspension damping may be increased so as to damp out thetransition pitching motion due to the pulse. Next, Method 700 continuesat 760 where QSP Traction Damping is performed. For example, suspensiondamping at one or more wheels may be increased to increase traction. Asa further example, suspension damping at one or more wheels may beincreased to the maximum value when the throttle 262 is above an enginethrottle threshold to increase or fully utilize the tractioncapabilities at one or more wheels.

Returning to method 700 at step 710, if the PG speed-control strategy iscurrently operating in a glide phase, method 700 continues to 770 whereit determines if vehicle 400 has an active suspension system. If vehicle400 has an active suspension system, method 700 continues at 780 whereQuasi-straight line Driving Glide (QSG) Leveling is performed. Forexample, QSG Leveling may first zero out any suspension heightadjustments used during the pulse phase (e.g., during QSP Leveling).Furthermore, during glide phases, sudden deceleration after shutting offthe engine or deactivating one or more cylinders may lead to vehiclenose-down (e.g., vehicle dive) which can increase passenger discomfort.QSG Leveling can adjust one or more wheel suspensions heights and canfirm the front suspension to maintain constant or near-constant vehicleheights. In addition, QSG Leveling may pre-position and pre-fill thesuspension actuators just prior to or at the start of the glide phase,in anticipation of the impending glide disturbance. In this mannervehicle pitching resulting from the glide phase deceleration can befurther reduced.

If vehicle 400 does not have an active suspension system, method 700continues at step 790, where QSG Motion Damping may be performed forvehicles equipped with semi-active (adaptive) suspension systems orcontrollable dampers (e.g., shocks). For example, suspension damping maybe increased so as to damp out the transition pitching motion during theengine throttle drop-off when the engine is shut off.

As a further example, if vehicle 400 is travelling on a slippery roadsurface (e.g., indicated by one or more of vehicle sensors 590), thevehicle TCS may limit the engine torque below a threshold engine torquetriggering TCS activation during pulse phases so as to reduce fractionor energy loss due to wheel spinning. Under these conditions, enginetorque application during pulse phases may still generate wheel slip,but the wheel slip will be below the TCS activation slip ratio.Furthermore, the PG Strategy submodule 550 may switch to Quasi-straightline driving Damping Pulse (QSDP) TCS mode, during which the suspensionis firmed via VDCM 512 at all times in order to increase vehicletraction.

After performing any one of 750, 760, 780, and 790, method 700 returnsto 660 of FIG. 6 from where it originated.

Turning now to FIG. 8, it illustrates an example method 800 for AQSPG,coordinating adaptive cruise control of Cruise Control/Forward SensingModule 514 with control of the suspension system, for example an activesuspension system via

VDCM 512, and PG speed-control strategy. Method 800 begins at 820 wherevehicle PG operating conditions are determined such as distance, d, of avehicle in front of vehicle 400, peak pulse vehicle speed v_(ppeak),minimum glide vehicle speed v_(gmin), pulse duration t_(p), and glideduration t_(g). Peak pulse vehicle speed and minimum glide vehicle speedcan be determined from the PG target speed and the PG thresholdinterval, while pulse duration and glide duration can be determined fromthe PG modulation period. Next, method 800 continues at 840 where PGoperating conditions are optimized based on distance, d. For example,t_(p) and t_(g) may be used to schedule suspension control, includingpre-adjusting vehicle suspension systems (e.g., an active suspensionsystem via VDCM 512) to anticipate PG operation and maintain constant ornear-constant vehicle heights while maintaining fuel economy andreducing passenger discomfort, and while maintaining a distance, d, froma vehicle travelling in front of vehicle 400. Furthermore, optimizationof AQSPG may be performed based on more advanced optimizationalgorithms. For example, AQSPG may coordinate control of several systemssuch as ESC/RSC and ABS/TCS of ABS Module 516 and Lane Departure Warningsystem of Cruise Control/Forward Sensing Module 514, VDCM 512, and PCM510 in conjunction with operation of the vehicle in AQSPG to maintainvehicle height, reduce passenger discomfort and maintain fuel economy.

In this manner, a method may comprise modulating vehicle speed about atarget speed by repeatedly operating one or more engine cylinders toincrease vehicle speed, and then deactivating one or more enginecylinders to reduce vehicle speed, and adjusting a vehicle suspensionsystem based on the cylinder operation to control vehicle pitch duringthe vehicle speed modulation. Furthermore, modulating the vehicle speedabout the target speed may comprise modulating the vehicle speed aboutthe target speed over a threshold interval, operating one or more enginecylinders to increase vehicle speed may comprise accelerating thevehicle over the threshold interval about the target speed, anddeactivating one or more engine cylinders to reduce vehicle speed maycomprise decelerating the vehicle over the threshold interval about thetarget speed.

Further still, adjusting the suspension system may comprise adjustingoperation of an active suspension system or adjusting operation of asemi-active suspension system. Adjusting operation of the suspensionsystem may comprise maintaining a constant front vehicle height duringthe modulating of vehicle speed about the target speed by adjusting atleast one of a front suspension height, a rear suspension height, afront suspension damping, and a rear suspension damping. Adjustingoperation of the active suspension system may further comprise at leastone of adjusting a front suspension height and adjusting a rearsuspension height, firming a front suspension and firming a rearsuspension. Further still, adjusting operation of the semi-activesuspension system may comprise increasing suspension damping, includingincreasing the suspension damping to its maximum value when an enginethrottle is above a threshold engine throttle.

Modulating the vehicle speed over the threshold interval may beperformed by a cruise control system onboard the vehicle. Furthermore,adjusting the suspension system may at least one of pre-positioning thesuspension heights and pre-filling the suspension actuators just priorto accelerating and decelerating the vehicle over the threshold intervalvia the cruise control system. Pre-positioning the suspension heightsand pre-filling the suspension actuators may be performed by a controlsystem on board the vehicle based on at least one of the target speed,the threshold interval, a modulation frequency for modulating thevehicle speed over the threshold interval about the target speed, and adistance from a second vehicle traveling in front of the vehicle.

Modulating the vehicle speed may further comprise limiting the thresholdinterval and/or the modulation frequency based on one or more of thetarget speed, a road surface roughness, a road grade, and a trailer towstatus. Modulating a vehicle speed may further comprise modulating ahybrid electric vehicle speed.

Furthermore, a method may comprise during vehicle-controlled speedregulation, operating one or more engine cylinders to increase thevehicle speed, and then deactivating one or more engine cylinders toreduce the vehicle speed without a change in driver pedal request, andadjusting a vehicle suspension system responsive to thevehicle-controlled speed regulation and in coordination with timing ofthe increase and decrease in vehicle speed. Further still, all enginecylinders may be fully activated to increase vehicle speed, and allcylinders may be fully deactivated, but still rotating, to decreasevehicle speed.

As explained above, the method of controlling the vehicle, such asduring cruise-control operation, may include operating one or moreengine cylinders to increase the vehicle speed, and then deactivatingone or more engine cylinders to reduce the vehicle speed without achange in driver pedal request. In synchronism with this periodiccruise-control operation, the method may further include adjusting avehicle suspension system responsive to the vehicle-controlled speedregulation and in coordination with timing of the increase and decreasein vehicle speed. The coordination can take into account expectedminimum and maximum vehicle speeds, and thus may predict based oncurrent vehicle speed and acceleration/deceleration, a timing of suchtransitions and thus control the suspension based on such anticipatedtiming.

Note that the example process flows described herein can be used withvarious engine and/or vehicle system configurations. The process flowsdescribed herein may represent one or more of any number of processingstrategies such as event-driven, interrupt-driven, multi-tasking,multi-threading, and the like. As such, various acts, operations, orfunctions illustrated may be performed in the sequence illustrated, inparallel, or in some cases omitted. Likewise, the order of processing isnot necessarily called for to achieve the features and advantages of theexample embodiments described herein, but is provided for ease ofillustration and description. One or more of the illustrated acts orfunctions may be repeatedly performed depending on the particularstrategy being used. Further, the described acts may graphicallyrepresent code to be programmed into the computer readable storagemedium in the engine control system.

It will be appreciated that the configurations and routines disclosedherein are exemplary in nature, and that these specific embodiments arenot to be considered in a limiting sense, because numerous variationsare possible. For example, the above technology can be applied to V-6,I-4, I-6, V-8, V-10, V-12, opposed 4, and other engine types. Thesubject matter of the present disclosure includes all novel andnon-obvious combinations and subcombinations of the various systems andconfigurations, and other features, functions, and/or propertiesdisclosed herein.

The following claims particularly point out certain combinations andsubcombinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims are to be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and subcombinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application.

1. A method, comprising: modulating a vehicle speed about a target speedduring cruise control operation by repeatedly operating one or moreengine cylinders to increase the vehicle speed, and then deactivatingone or more engine cylinders to reduce the vehicle speed, via a controlsystem; and adjusting a vehicle suspension system based on the cylinderoperation to control vehicle pitch during the vehicle speed modulation.2. The method of claim 1, wherein modulating the vehicle speed about thetarget speed comprises modulating the vehicle speed about the targetspeed over a threshold interval.
 3. The method of claim 2, whereinoperating one or more engine cylinders to increase the vehicle speedcomprises accelerating the vehicle over the threshold interval about thetarget speed and wherein deactivating one or more engine cylinders toreduce vehicle speed comprises decelerating the vehicle over thethreshold interval about the target speed.
 4. The method of claim 3,wherein adjusting the suspension system includes adjusting operation ofan active suspension system via the control system.
 5. The method ofclaim 3, wherein adjusting the vehicle suspension system comprisesadjusting operation of a semi-active suspension system via the controlsystem.
 6. The method of claim 4, wherein adjusting operation of thevehicle suspension system comprises reducing disturbances to frontvehicle height during the modulating of vehicle speed about the targetspeed by adjusting at least one of a front suspension height, a rearsuspension height, a front suspension damping, and a rear suspensiondamping, via the control system.
 7. The method of claim 4, whereinadjusting operation of the active suspension system comprises at leastone of adjusting a front suspension height and adjusting a rearsuspension height via the control system.
 8. The method of claim 7,wherein adjusting operation of the active suspension system furthercomprises at least one of firming a front suspension and firming a rearsuspension, via the control system.
 9. The method of claim 5, whereinadjusting operation of the semi-active suspension system comprisesincreasing a suspension damping via the control system.
 10. The methodof claim 9, wherein increasing the suspension damping comprisesincreasing the suspension damping to its maximum value when an enginethrottle is above a threshold engine throttle.
 11. The method of claim3, wherein modulating the vehicle speed over the threshold interval isperformed by a cruise control system onboard the vehicle, wherein thecontrol system includes the cruise control system.
 12. The method ofclaim 11, wherein adjusting the vehicle suspension system comprises atleast one of pre-positioning suspension heights and pre-fillingsuspension actuators based on upcoming vehicle acceleration anddeceleration over the threshold interval via the cruise control system.13. The method of claim 12, wherein pre-positioning the suspensionheights and pre-filling the suspension actuators is performed by acontrol system on board the vehicle based on at least one of the targetspeed, the threshold interval, a modulation frequency for modulating thevehicle speed over the threshold interval about the target speed, and adistance from a second vehicle traveling in front of the vehicle. 14.The method of claim 13, wherein modulating the vehicle speed furthercomprises limiting the threshold interval based on one or more of thetarget speed, a road surface roughness, a road grade, and a trailer towstatus.
 15. The method of claim 13, wherein modulating the vehicle speedfurther comprises limiting the modulation frequency based on one or moreof the target speed, a road surface roughness, a road grade, and atrailer tow status.
 16. A vehicle, comprising: an engine; a suspensionsystem; and a control system including one or more controllers, anetwork, and one or more memories with instructions executable storedtherein to modulate a vehicle speed about a target speed by operatingthe vehicle with the engine at increased output and then with the engineoff, and adjust suspension system operation based on the vehicleoperation to control vehicle pitch during the modulating of the vehiclespeed about the target speed.
 17. The vehicle of claim 16, wherein thesuspension system comprises a least one of an active suspension systemand a semi-active suspension system.
 18. The vehicle of claim 17,wherein the control system comprises a smart adaptive cruise controlsystem.
 19. A method for a control system of a vehicle, comprising: viathe control system: during vehicle-controlled speed regulation,operating one or more engine cylinders to increase the vehicle speed,and then deactivating one or more engine cylinders to reduce the vehiclespeed without a change in driver pedal request; and adjusting a vehiclesuspension system responsive to the vehicle-controlled speed regulationand in coordination with timing of the increase and decrease in vehiclespeed.
 20. The method of claim 19, wherein all engine cylinders arefully activated to increase vehicle speed, and all cylinders are fullydeactivated, but still rotating, to decrease vehicle speed.